Consider additives to stop leaks in cooling and other systems as patchwork.
It can be helpful, but it also can do damage.
Only today a - not DeLorean - car owner complains that after using a leak stopper for his cooling system turned into a nightmare.
Clogged radiator, thermostat and perhaps channels in the engine block causing overheating.
What applies to the cooling system could also happen in the engine block's oil channels.
If that happens cleaning is almost impossible, leaving the owner with no other choice than replacement.
That then requires a deep and well filled purse!
IMO it's better to stay away from this additive type solution and go for the proper repair track.

